They found that 16% of the women reported breast cancer in a relative on their mother's side of the family. But only 10% reported breast cancer in a relative on their father's side of the family.

The most likely explanation for this is that women simply underreport breast cancer when it occurs in their fathers' families.

"Patients may not know that paternal family history is also relevant for their health," Quillin and colleagues conclude. "Primary care physicians might pay particular attention to getting information about the father's side of the family."

Quillin and colleagues report their findings in the September issue of the American Journal of Preventive Medicine.